function mostrarBanner() 
{ 
 
total=3; 
banner = Math.floor(Math.random() * total); 
 
switch(banner) 
{ 
case 0: 
document.write("<A HREF=' http://www.alborde.com.ar ' TARGET='_blank'><IMG SRC='imagenes/banner_1.gif' BORDER='0'></A>"); 
break; 
case 1: 
document.write ("<A HREF='http://www.pierobonmountain.com.ar' TARGET='_blank'><IMG SRC='imagenes/banner_2.gif' BORDER='0'></A>"); 
break; 
case 2:
document.write("<A HREF=' http://www.posadadelaguamendoza.com' TARGET='_blank'><IMG SRC='imagenes/banner_3.gif' BORDER='0'></A>"); 
break; 
} 
 
}